Vibration linear actuating device, method of driving the same device, and portable information apparatus using the same device

ABSTRACT

A vibration linear actuating device includes a vibrating linear actuator and a driver ( 52 ) for driving actuator. Actuator includes mover having permanent magnet magnetized in a radial direction, stator having coil ( 2 ) and facing the permanent magnet, and elastic body for coupling stator to mover. The driver includes driving section having switching element (Q 5 ) for powering coil ( 2 ), output controller ( 27 ) for controlling switching element (Q 5 ), zero-cross detector ( 25 ) for detecting a zero-cross point of back electromotive force generated in coil ( 2 ) and having an output to be fed back to the output controller ( 27 ). In this structure, the driver powers coil ( 2 ) in one way to keep mover vibrating in corporation with elastic body.

THIS APPLICATION IS A U.S. NATIONAL PHASE APPLICATION OF PCTINTERNATIONAL APPLICATION PCT/JP03/04200.

TECHNICAL FIELD

The present invention relates to electromagnetic vibrators, i.e.,vibration linear actuating devices, a method for driving the samedevices, and portable information apparatuses using the same device.More particularly, it relates to a method for driving theelectromagnetic vibrator positively in a stable manner at an inexpensivecost.

BACKGROUND ART

A vibration generator is used as a pager in portable informationapparatuses such as cellular phones. A conventional vibration generatorhas employed a cylindrical motor equipped with an unbalancing weight.However, the cylindrical motor has a ceiling of being slimmed down, andis hard to be mounted onto a board by an automatic mounting machine. Acoin-shaped motor equipped with an unbalancing weight is commercializedfor overcoming the foregoing problems; however, its vibrating directionis in parallel with the printed circuit board, so that the vibration ishard to be sensed. A button-shaped vibration linear actuating device isproposed in order to generate vibrations vertical to the board; however,a greater exciting force cannot compatible with a slimmer body. Aconventional vibration linear actuating device, in general, employs apush-pull driving circuit using four switching elements. This isdisclosed in Japanese Patent Application Non-examined Publication No.2001-25706.

FIG. 15 shows a circuit diagram of the conventional actuating device.Starter 61, output controller 62, driving-pulse setter 63, and driver 64formed of four switching elements Q11-Q14 coupled together into a bridgestructure. Coil 65 of the vibration actuating device is coupled to amiddle point of the bridge structure, and driver 64 drives coil 65. Thisactuating device has numbers of elements in the driving circuit, and amovement of the mover along a positive direction or a negative directionneeds to be powered every time. Thus the foregoing structure needscomplicated control and consumes a lot of power.

There are other prior art disclosed in PCT International Publication No.WO99/40673, Japanese Patent Application Non-Examined Publication Nos.2000-14190 and H11-0.197601. The present invention discloses a vibrationlinear actuating device, a method of driving the same device, and aportable information apparatus employing the same device that has anovel structure different from those prior art.

DISCLOSURE OF THE INVENTION

The vibration linear actuating device of the present invention comprisesa vibrating linear actuator and a driver for driving the actuator. Thevibrating linear actuator includes the following elements:

a mover having a permanent magnet magnetized in a radial direction;

a coil;

a stator facing the permanent magnet; and

an elastic body for coupling the stator to the mover and for energizingthe mover toward a center of the stator.

The driver includes the following elements:

a driving section having a switching element for powering the coil;

an output controller for controlling the switching element; and

a zero-cross detector for detecting a zero-cross point of backelectromotive force (BEMF) generated in the coil and for outputting azero-cross signal.

In this structure, the driver transmits the zero-cross signal to theoutput controller and powers the coil in one direction, therebyvibrating the mover in cooperation with the elastic body.

The present invention further discloses a method for driving thevibration linear actuating device as well as a portable informationapparatus equipped with the vibration linear actuating device.

The present invention can provide a slim and highly efficient vibrationlinear actuating device as well as a portable information apparatus, sothat portability of the apparatus and durability of batteries areadvantageously improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sectional view of a vibrating linear actuator inaccordance with a first exemplary embodiment of the present invention.

FIG. 2 is a circuit diagram of a driver in accordance with the firstexemplary embodiment of the present invention.

FIG. 3 is a circuit diagram of a function for monitoring a zero-crossdetecting signal in accordance with the first exemplary embodiment ofthe present invention.

FIG. 4 is a timing chart illustrating the monitoring function.

FIG. 5 is a circuit diagram of a function for re-starting the zero-crossin accordance with the first exemplary embodiment of the presentinvention.

FIG. 6A and FIG. 6B show timing charts illustrating the re-startingfunction.

FIG. 7 is a flowchart of processing a signal by the driver.

FIG. 8 shows a hardware structure of the driver.

FIG. 9 is a timing chart illustrating the signal processing.

FIG. 10 is a circuit diagram of a driver in accordance with a secondexemplary embodiment of the present invention.

FIG. 11 is a circuit diagram of a driver in accordance with a thirdexemplary embodiment of the present invention.

FIG. 12 shows a timing chart illustrating an operation of the driver inaccordance with the third exemplary embodiment of the present invention.

FIG. 13 is a circuit diagram of a driver in accordance with a fourthexemplary embodiment of the present invention.

FIG. 14 shows a sectional view illustrating a structure of a portableinformation apparatus in accordance with a fifth exemplary embodiment ofthe present invention.

FIG. 15 shows a circuit structure of prior art.

PREFERRED EMBODIMENTS OF THE INVENTION

Exemplary embodiments of the present invention are demonstratedhereinafter with reference to the accompanying drawings.

Exemplary Embodiment 1

FIG. 1 shows a structure of vibrating linear actuator 1, which comprisesthe following elements:

-   -   mover 4A including;        -   polygonal outer yoke 4; and        -   permanent magnet 5 disposed inside outer yoke 4,    -   stator 3A disposed inside mover 4A and including:        -   tubular inner yoke 3 having teeth at its upper and lower            sections with a space between the upper and lower teeth; and        -   coil 2 wound on inner yoke 3.

Permanent magnet 5 is magnetized, e.g., N pole at its inner wall and Spole at its outer wall, i.e., the inner wall and the outer wall aremagnetized unipolar respectively and different poles from each other.Inner yoke 3 and outer yoke 4 are formed of metallic material made fromgreen compact of magnetic powder, however; they can be formed of thinsteel plates laminated radially (thin steel plates are laminated onshaft 8 radially).

Besides, inner yoke 3 and outer yoke 4 can be formed by drawing steelplates, cylindrical steels, ring shaped steels and the like.Furthermore, inner yoke 3 and outer yoke 4 can be made of resincontaining metal powders. As discussed above, various materials orproducing methods of inner yoke 3 and outer yoke 4 can be considered,and this invention is not limited to the materials and the methodsmentioned above.

Inner yoke 3 has shaft 8 at its center, and shaft 8 protrudes from abottom plate of inner yoke 3. Inner yoke 3 is positioned with theprotruding portion of shaft 8 and a recess of base 9, and rigidlymounted on base 9. A lower elastic body 6 is sandwiched by base 9 andinner yoke 3. Base 9 is made from heat-resistant resin of which glasstransition temperature is not less than 90° C.

Elastic body 6 is formed of two thin leaf springs (an upper spring and alower spring) shaped like rings. When mover 4A moves downward from abalanced point, elastic body 6 moves mover 4A upward. When mover 4Amoves upward from the balanced position, elastic body 6 moves mover 4Adownward. In other words, elastic body 6 energizes mover 4A to bepositioned at substantially the midpoint of stator 3A.

Coil 2 is electrically coupled to metallic land 11 extending from thebottom of base 9, and powered from land 11. Land 11 can be prepared on atop face of cover 7 instead of the bottom of base 9.

Cover 7 covers stator 3A and mover 4A, and is caulked to base 9 withcover-caulking section 10 prepared to base 9. Cover 7 protects thecomponents inside of the actuator from touching other components outsidethe actuator or from damages when the actuator undergoesreflow-soldering.

Cover 7 also helps handling of the actuator. Cover 7 is made from metal;however, it can be made from heat-resistant resin.

Actuator 1 discussed above flows the current supplied from land 11 tocoil 2, thereby generating vibrating magnetic flux. Mover 4A vibratesfollowing this vibrating magnetic flux.

FIG. 2 shows a basic structure of a driver that drives this vibratinglinear actuator. In FIG. 2, starter 21 is shown schematically as switch21A, and it starts the actuator like an arrival signal in a portableinformation apparatus.

Driving section 22 is formed of the following elements: a first end ofcoil 2 is coupled to a positive electrode of circuit power-source Vccand a second end thereof is coupled to a collector terminal ofswitching-element Q5, which is formed of NPN transistor and drives coil2. An emitter terminal of switching element Q5 is coupled to thenegative electrode (grounding potential) of the circuit power sourceVcc. The second end of coil 2 is coupled to zero-cross detector 25 vialevel-shift section 24 and back electromotive force (BEMF) amplifier 23,thereby detecting a zero-cross point of the BEMF. In other words, thezero-cross point of the BEMF is to detect a point where the amplitude ofactuator 1 becomes maximum. The signal that detects the maximumamplitude point is fed back to output controller 27, so that drivingsection 22 works positively in a stable manner.

An operation of the circuit shown in FIG. 2 is detailed hereinafter.Switch 21A of starter 21 is turned on, then signal H is fed into inputterminal B of one-shot multi-vibrator 33. On the other hand, inputterminal Ā is in status L at the initial stage, so that its outputterminal Q outputs pulses of level H having a set time-span. This pulseof level H runs through OR circuit 27B and turns on switching elementQ5, and arrives at coil 2 to power it. One-shot multi-vibrator 33 hasanother input terminal (not shown) to be used for a time-constant, and acapacitor and a resistor are coupled to this input terminal, therebysetting the time span.

Coil 2 is powered and the actuator is started, then BEMF is generatedfrom coil 2 and fed into zero-cross detector 25 via level-shift section24 and BEMF amplifier 23. Level-shift section 24 adjusts a signal levelof BEMF waveform in response to power-source voltage Vcc, and benefitsthe circuit power-source Vcc to be unified. It can set the referencevoltage of BEMF amplifier 23 at any value, e.g., a half of Vcc to complywith the circuit power-source Vcc.

Zero-cross detector 25 compares an input from amplifier 23 with azero-cross voltage, and inverts the input with inverter element 25B,then outputs signal SX.

This signal SX and a signal of level H of switch 21A are respectivelyfed into a first input terminal and a second input terminal of NANDelement 32, which then outputs signal SX. This signal SX is fed into aninput terminal of AND element 26A of zero-cross detecting monitor 26.Another input terminal of AND element is in a status of level H at theinitial stage, thus AND element 26A outputs signal SY on the same logiclevel as signal SX.

One-shot multi-vibrator 27A of output controller 27 receives signal SYat its input terminal B, and turns to level H, then its output terminalQ outputs pulse SA having the set time-span. One-shot multi-vibrator 27Ahas another input terminal (not shown) to be used for a time-constant,and a capacitor and a resistor are coupled to the input terminal,thereby setting the time span. The pulse of level H turns on switchingelement Q5 via OR element 27B, and at the same time, this pulse is fedinto input terminal Ā of multi-vibrator 26B. Another input terminal B ofvibrator 26B is fixed at level H, thus pulse SM of level L having theset time-span is tapped off from output terminal Q at the falling edge(level H→level L) of the input signal fed into input terminal Ā.One-shot multi-vibrator 26B has another input terminal (not shown) to beused for a time-constant, and a capacitor and a resistor are coupled tothe input terminal, thereby setting the time span. An output of level Lfrom multi-vibrator 26B is fed into AND element 26A, and signal SY isforcibly fixed at level L. In other words, the pulse of level L masks aread-error of a zero-cross pulse. (More details will be describedlater.)

When zero-cross detector 25 does not output signal SX clue to, e.g., ahalt of the vibrating linear actuator, an output signal from terminal Qof one-shot multi-vibrator 31 turns to level L in the set time-span fromthe rising of the signal. This falling signal (level H→level L) is fedas a trigger signal into input terminal Ā of one-shot multi-vibrator 33,which then outputs pulse H having the time-span set by vibrator 33, sothat the actuator restarts.

When switch 21A of starter 21 is turned off, the second input terminalof NAND element 32 turns to level L, so that the actuator halts.

Diode D1 of driving section 22 protects switching element Q5 when theBEMF of coil 2 becomes extraordinarily high.

An NPN transistor is used in switching element Q5 of driving section 22;however, a PNP transistor can be used instead. In this case, the emitterof the PNP transistor is coupled to the positive electrode ofpower-source Vcc, and the collector is coupled to a first end of thecoil, and a second end of the coil is coupled to the negative electrode(grounding potential) of power-source Vcc. This structure allows thefirst end of the coil to detect the zero-cross point of the BEMF.

A function (masking function) of monitoring a zero-cross detectingsignal is detailed with reference to FIG. 3 and FIG. 4. FIG. 3 shows thesection of the monitoring function selected from FIG. 2. Reference marksSB, SX, SM, SY, and SA represent signals of respective elements, andcorrespond to the waveforms in FIG. 4 marked with the same referencemarks.

Waveform SB of the BEMF produced by coil 2 is shaped by zero-crossdetector 25, and is tapped off as waveform SX. Then it is inverted byNAND element 32 (not shown), so that waveform SX is output; however thiswave-form includes error signals marked with shading in FIG. 4. WaveformSM is a mask signal generated by one-shot multi-vibrator 26B, and fedback to AND element 26A, thereby removing the error signals. As aresult, correct zero-cross signal SY is obtained. This signal SY isoutput as signal SA by one-shot multi-vibrator 27A, and then fed intoswitching element Q5. Signal SA is omitted in FIG. 4, however, signal SAbecomes the same as signal SY.

Next, the restarting function is detailed with reference to FIGS. 5, 6Aand 6B. FIG. 5 shows the section of restarting function selected fromFIG. 2. FIGS. 6A and 6B show timing charts of zero-cross detectingsignal SY and hold-signal SH. FIG. 6A shows a case where zero-crosssignals are sequentially detected, and FIG. 6B shows a case where azero-cross signal is failed to be detected. As shown in FIG. 6B, afailure of detecting the zero-cross signal changes hold-signal SH tolevel L in a given time, so that multi-vibrator 33 produces are-starting pulse thereby restarting the actuator.

FIG. 7 shows a flowchart illustrating the processing of signals in theactuating device in accordance with the first embodiment. Timer I, II,III, and IV are timing setters and correspond to one-shotmulti-vibrators 27A, 33, 26B, and 31 shown in FIG. 2 respectively. Theflow of FIG. 7 illustrates software-wise the process in the actuatingdevice.

Respective timers operate as follows: Timer I determines a width of workpulse, so that it determines a period of powering coil 2 in respectivecycles. Timer I starts counting at decision Yes of BEMF zero-cross andhalts the powering at count-up.

Timer II determines a width of a starter pulse, so that it determines aperiod of powering coil 2 at starting. Timer II starts counting with astarter signal and halts the powering at count-up.

Timer III determines a width of a mask pulse, and starts counting whentimer I counts up. Timer III keeps masking the zero-cross determinationsuntil it counts up.

Timer IV determines a width of a hold pulse, and starts counting atdecision Yes of zero-cross, and the operation returns to timer II whenit counts up.

Next, the flowchart shown in FIG. 7 is detailed. First, switch 21A ofstarter 21 is turned on, then when drive determination and startdetermination are Yes, timer II starts working for outputting anactuator starter pulse. The starter pulse of which width is thetime-span of timer II is supplied to power coil 2, and the actuatorforcibly starts driving. When timer II counts up, the supply of thestarter pulses is turned off, so that the powering to the coil ishalted. Then the BEMF of coil 2 is monitored, and when zero-crossdetermination is Yes, the powering to coil 2 starts again, and both oftimer I and timer IV start counting. When timer I counts up, thepowering to coil 2 is halted, and at the same time timer III startscounting. When timer III counts up, this loop is fed back to the startsignal. If zero-cross determination is Yes again before timer IV countsup, the count of timer IV is reset. However, if timer IV counts up withits count being left non-reset, this loop is fed back to a starterdetermining section. In other words, when the actuator is halted due tofailure in determining a zero-cross, coil 2 is powered for restartingthe actuator. If no starter signal is available, the output controlleris turned off and all the timers I-IV are halted.

The foregoing process can be carried out with ease using the flowchartshown in FIG. 7 by software built in a micro-processor. The hardwareconstruction in such a case is shown in FIG. 8. The BEMF is fed intomicro-processor controller 42 via analog-digital converter 41, therebydetecting the zero-cross of the BEMF produced by coil 2 of the actuator,and at the same time the switching element is driven at an optimumtiming. If the BEMF undergone the A-D conversion is fed into themicro-processor, any timing other than the zero-cross of BEMF can bedetected, so that the timing of the driving pulse can be controlled atany position of mover 4A. For instance, the maximum amplitude (eitherpositive or negative) of the BEMF is detected, and the driving pulse ofthe actuator is output. An experiment proves that the driving pulse issupplied most efficiently at this timing.

FIG. 9 shows a timing chart illustrating a positional relation betweenthe BEMF waveform and mover 4A. The zero-cross point of BEMF correspondsto the largest displacement point of mover 4A. The zero-cross point ofBEMF waveform appears at the point where ¼ cycle is delayed from thezero-cross point of mover 4A. At either one of those timings, theswitching element can be driven. However, switching element Q5 is turnedon during a period including the zero-cross point of mover 4A, andkinetic energy is given to mover 4A when mover 4A moves at its maximumspeed. Then the switching element can be driven most efficiently.

As discussed above, the present invention includes a function ofdetecting a zero-cross point of BEMF of coil 2, and the powering of thecoil in only one-way can excites mover 4A. In other words, mover 4A canbe moved in a positive direction by electromagnetic force obtained bypowering coil 2, and it can be moved in a negative direction byrepulsion or attraction of elastic body 6, so that less powerconsumption can be achieved.

The BEMF generated from an end of coil 2 is directly used to detect azero-cross point of the BEMF, so that additional components for thedetection are not needed, and a simple structure can be achieved.

Exemplary Embodiment 2

FIG. 10 shows a circuit structure of a vibration linear actuating devicein accordance with the second exemplary embodiment of the presentinvention. The device used in the second embodiment includes pulse-widthmodulator 46 in addition to the circuit shown in FIG. 2, so that asmaller coil resistance is expected, which is particularly effectivewhen an over current flows in turning on switching element Q5. Modulator46 modulates a pulse width of a signal supplied from the outputcontroller as an input signal to the switching element, so that theactuator can be driven in a stable manner and yet the power consumptioncan be lowered.

Exemplary Embodiment 3

FIG. 11 shows a circuit structure of a vibration linear actuating devicein accordance with the third exemplary embodiment of the presentinvention. The device used in the third embodiment includes timingadjuster 47, formed of two-stage flip-flop circuit, in addition to thecircuit shown in FIG. 2. As shown in a timing chart of FIG. 12,switching element Q5 is turned on with a delay of time “t” from azero-cross point of BEMF, thereby outputting an actuator-driving pulseat any timing delayed from a zero-cross point of BEMF. As a result, theactuator can be driven at a position close to the zero-cross point ofmover 4A, because this point is experimentally proved efficient.

Exemplary Embodiment 4

FIG. 13 shows a circuit structure of a vibration linear actuating devicein accordance with the fourth exemplary embodiment of the presentinvention. The device used in the fourth embodiment includes phaselocked loop (PLL) 48 as a timing adjuster in addition to the circuitshown in FIG. 2. This structure allows generating a signal for drivingthe switching element Q5 at any tiling with respect to the vibrations ofmover 4A even if a resonance point of actuator 1 varies with referenceto a zero-cross detecting signal.

Exemplary Embodiment 5

A portable information apparatus, e.g., cellular phone, equipped withthe vibrating linear actuator of the present invention, in accordancewith the fifth exemplary embodiment of the present invention isdemonstrated hereinafter. FIG. 14 shows a sectional view illustratingthe structure of the apparatus. Actuator 1 shown in FIG. 1 is directlymounted on apparatus board 51 with its shaft (shaft 8 shown in FIG. 1)kept standing vertically.

The terminal land (land 11 shown in FIG. 1) provided beneath actuator 1is directly brazed to the land provided to the upper face of board 51.Driver 52 of actuator 1 is mounted on board 51 together withcircuit-components of the apparatus. Housing 53 of apparatus 50 housesbattery 54 therein, and battery 54 powers the apparatus circuit anddriver 52. When a coil of an inner yoke of the actuator is powered, itsmagnetic field attracts or repels an outer yoke, and when the poweringto the coil is halted, the outer yoke reacts to a leaf spring (elasticbody). As a result, actuator 1 vibrates such that an amplitude of thevibration becomes maximum in a direction vertical to a surface of board51. In the case of a cellular phone, it adopts an arrival signal as astarter signal for actuator 1, thereby operating actuator 1, and thevibrations of actuator 1 can be sensed by a user as an arrival signalvibrating in a maximum amplitude.

INDUSTRIAL APPLICABILITY

Powering a coil of an actuator can be controlled by on-off of a singleswitching element. A zero-cross of BEMF of the coil is detected, and thedetection signal is fed back to an output controller, so that a circuitof a driver is simplified. As a result, the driver operates positivelyin a stable manner, and can work with less power consumption.

A major system of drive-control of the actuator can be controlled withease by a micro-processor, so that a vibration linear actuating devicecan be further downsized.

A slimmed down and highly efficient vibration linear actuating deviceand a portable information apparatus equipped with this device can beprovided. Therefore, portability of the apparatus and durability ofbatteries can be improved.

1. A vibration linear actuating device comprising a vibrating linearactuator and a driver for driving the actuator; the vibrating linearactuator including: (a) a mover having a permanent magnet magnetized ina radial direction; (b) a stator having a coil and facing the permanentmagnet; and (c) an elastic body for coupling the stator to the mover andenergizing the mover toward a center of the stator, the driverincluding: (d) a driving section having a switching element for poweringthe coil; (e) an output controller for controlling the switchingelement; and (f) a zero-cross detector for detecting a zero-cross pointof back electromotive force (BEMF) generated in the coil and outputtinga zero-cross signal, wherein the driver transmits the zero-cross signalto the output controller and powers the coil in one direction forvibrating the mover in corporation with the elastic body.
 2. Thevibration linear actuating device of claim 1, wherein the driver furtherincludes a zero-cross monitor disposed between the zero-cross detectorand the output controller.
 3. The vibration linear actuating device ofclaim 2, wherein the zero-cross monitor monitors the zero-cross signaland does not permit receiving a next zero-cross signal for a given timeafter the monitor receives the zero-cross signal.
 4. The vibrationlinear actuating device of claim 1, wherein the driver transmits are-starter signal to the output controller when the zero-cross signal ishalted for a given time.
 5. The vibration linear actuating device ofclaim 1, wherein the zero-cross detector is coupled to the coil via aBEMF amplifier and a level-shift section.
 6. The vibration linearactuating device of claim 1, wherein the driver further includes atiming adjuster disposed between the zero-cross detector and the outputcontroller.
 7. The vibration linear actuating device of claim 6, whereinthe timing adjuster includes a phase locked loop.
 8. The vibrationlinear actuating device of claim 1, wherein the output controllerincludes a pulse width modulator.
 9. A method of driving an vibratinglinear actuator, the actuator comprising: a mover having a permanentmagnet magnetized in a radial direction; a stator having a coil andfacing the permanent magnet; and an elastic body for coupling the statorto the mover and energizing the mover toward a center of the stator, themethod comprising the steps of: (a) determining a zero-cross point ofback electromotive force generated in the coil; (b) determining a periodfor powering the coil in every cycle; (c) determining a period forpowering the coil at starting time; and (d) counting step (b) based onthe determined result of step (a).
 10. The method of driving anvibrating linear actuator of claim 9 further comprising step (e) forcounting for itself based on the determined result of step (a), whereinthe determined result of step (a) is kept invalid until step (e) countsup.
 11. The method of driving an vibrating linear actuator of claim 9further comprising step (f) for counting for itself based on thedetermined result of step (a), wherein step (c) starts counting whenstep (f) counts up.
 12. The method of driving a vibrating linearactuator of claim 11, wherein step (f) is reset depending on a nextdetermined result.
 13. A portable information apparatus comprising: (a)a board; (b) a vibrating linear actuator mounted to the board; theactuator including: (b-1) a mover having a permanent magnet magnetizedin a radial direction; (b-2) a stator having a coil and facing thepermanent magnet; and (b-3) an elastic body for coupling the stator tothe mover and energizing the mover toward a center of the stator, (c) adriver mounted to the board, the driver including: (c-1) a drivingsection having a switching element for powering the coil; (c-2) anoutput controller for controlling the switching element; and (c-3) azero-cross detector for detecting a zero-cross point of backelectromotive force (BEMF) generated in the coil and outputting azero-cross signal, wherein the driver transmits the zero-cross signal tothe output controller and powers the coil in one direction for vibratingthe mover in corporation with the elastic body.
 14. The portableinformation apparatus of claim 13, wherein the vibrating linear actuatorgenerates vibrations with a maximum amplitude in a vertical direction tothe board.
 15. The portable information apparatus of claim 13, whereinthe driver further includes a zero-cross monitor disposed between thezero-cross detector and the output controller.
 16. The portableinformation apparatus of claim 15, wherein the zero-cross monitormonitors the zero-cross signal and does not permit receiving a nextzero-cross signal for a given time after the monitor receives thezero-cross signal.
 17. The portable information apparatus of claim 13,wherein the driver transmits a re-starter signal to the outputcontroller when the zero-cross signal is halted for a given time. 18.The portable information apparatus of claim 13, wherein the zero-crossdetector is coupled to the coil via a BEMF amplifier and a level-shiftsection.
 19. The portable information apparatus of claim 13, wherein thedriver further includes a timing adjuster disposed between thezero-cross detector and the output controller.
 20. The portableinformation apparatus of claim 19, wherein the timing adjuster includesa phase locked loop.
 21. The portable information apparatus of claim 13,wherein the output controller includes a pulse width modulator.